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Corrosion on stainless steel

Corrosion on stainless steel

Corrosion on stainless steel

(OP)
Hey,
I Wonder how to deal with corrosion on stainless steel. Of course I mean other methods than electropolishing and pasivation.

RE: Corrosion on stainless steel

What type of corrosion do you observe? Cracking, pitting, staining???

RE: Corrosion on stainless steel

What is your fluid?

RE: Corrosion on stainless steel

What stainless? How was it fabricated and finished?
What is the environment?

The first step is always chemical passivation. Before it goes into service and before there is any corrosion. Passivation will remove traces of Fe from the surface that came from tools and handling. Often rust staining is no more than these spots corroding, but they can serve as sites for pitting to initiate also.

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P.E. Metallurgy, Plymouth Tube

RE: Corrosion on stainless steel

(OP)
Pitting corrosion on ss. It shows up after shipping - transport by ships throug ocean.
Fluid - water and gas.

RE: Corrosion on stainless steel

Many of our customers require shrink wrapping for ocean transport...

RE: Corrosion on stainless steel

Is it really 304? Protect by wrapping in plastic for ocean transport. It must be protected from sea water incursion.

RE: Corrosion on stainless steel

Is this a new pressure vessel?
Pitting inside, outside or both?

Regards
r6155

RE: Corrosion on stainless steel

Neither 304 or 316 can be expected to survive unprotected ocean shipment.
They must be fully protected, and even then I would not be surprised by some superficial corrosion.

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P.E. Metallurgy, Plymouth Tube

RE: Corrosion on stainless steel

(OP)
It's new product. Corrosion is inside and outside also.
Passivation solves the problem partly but i'm searching for other methods.

RE: Corrosion on stainless steel

Shrink wrap + N2 purge... quite common.

RE: Corrosion on stainless steel

daisypl, is your corrosion due to contamination with iron or carbon steel during the manufacturing process?

If so, you need to improve the processes taking care to prevent the contamination. Segregate the work. Use only new or segregated grinding wheels, wire brushes, drill bits etc. Cover plate rolls, forming tools, jigs, etc. with carpet, or use stainless tooling, and so forth. Then pickle and passivate.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

RE: Corrosion on stainless steel

My experience 40 years ago: After hydraulic test the vessel was drained over entire night. In the morning pitting was found in 100% surface.
Be careful with the quality of water during hydraulic test.

Your pressure vessel was inspected inside prior shiping ?

Regards
r6155

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